Effects of pork collagen on thermal and viscoelastic properties of purified porcine myofibrillar protein gels

Abstract

The objectives of this study were to examine the thermal, water-binding and viscoelastic properties of mixed protein systems containing purified myofibrils from porcine semimembranosus (MP) and pork collagen (PC) during gelation and subsequent cooling. MP:PC mixtures (100:0, 90:10, 80:20, 70:30, 60:40, 50:50) normalized to 4% protein were evaluated. No significant differences in thermal characteristics of these mixtures could be detected using differential scanning calorimetry. A primary peak was observed near 66 °C. Using small-strain oscillatory testing, the rheological properties during gelling and cooling were quantified. Storage modulus ( G′) increased upon heating for all treatments, but the rate of gel firming and the G′ value at 85 °C were significantly lower ( P<0.05) as PC was added to the mixed protein system. Upon cooling, gels revealed a significantly lower ( P<0.05) rate of gel firming and significantly lower ( P<0.05) G′ value at 5 °C in samples with 20% inclusion of PC and higher. Addition of PC yielded a significant linear ( R 2=0.65; P<0.01) increase in the water-holding capacity (WHC) of the gels, indicating that the matrix formed in MP:PC gels had a greater ability to entrap water than that of the control MP gels. The inclusion of 10% PC resulted in gels with significantly higher ( P<0.05) WHC and similar firmness when compared with gels comprised of MP as the only protein source.